Study on biological oceanography charateristics of planktonic copepods in waters north of Taiwan Ⅱ. Community characteristics

The Paper is the succession of the study on abundance distribution of planktonic copepods in the waters north of Taiwan, and the emphasis is laid on the analysis and discussion of the constructions and features of copepod community and the relationships with water environment. The results show as follows: a total of 237 species were identified and the construction of communtity was complex. The percentage of annual present species was only 32%. The mean values of diversity and homogeneity of the copepod community were 3. 714 and 0. 690 respectively, and their horizontal distribution patterns were higher in outshore area than in nearshore area. The copepods of the area could be divided into five ectotypes. Warm-water outshore high temperature and lower saline group and tropic oceanic high temperature and saline group could indicate the seasonal changes of the Taiwan Strait water and the Kuroshio surface water respectively. According to the various aspects of calculation and analysis, winter was different from other three seasons in environmental conditions. In spring, summer and autumn, Undinula valgaris was the meat dominant species and salinity was the main factor that affected the community feature values. The communities in the three seasons had the subtropic-tropic characteristics in which warm-water outshore species were dominant and tropic oceanic species accounted for also certain proportion. While in winter, the dominant species was Euchaeta manna and temperature was the main factor influencing the community feture values. The community had the tropic oceanic characteristics in which tropic oceanic species were dominant.

Distribution patterns of appendicularians and copepods and their relationship on the northwest continental shelf of South China Sea during summer

The potential suppression of copepods on appendicularians was found in field and experimental conditions. The abundance and distribution of appendicularians and planktonic copepods were studied with reference to their correlations during summer on the northwest continental shelf of the South China Sea （SCS）. Based on the topography and water mass of the surveyed region, it was divided into three sub-regions： Region I （inshore waters of the east Leizhou Peninsula） with low temperature, salinity and high chlorophyll a （Chl a） concentration, Region II （inshore waters of the east and southeast Hainan Island） with low temperature, high salinity and moderate Chl a concentration and Region III （offshore waters from the Leizhou Peninsula to Hainan Island） with high temperature, high salinity and low Chl a concentration. The species richness of appendicularians and copepods increased from the inshore to offshore waters, and high values were observed in Region III. The distribution of appendicularian and copepod abundance decreased generally from the inshore to offshore waters, with the highest values at Region I. Our results suggest that the distribution patterns of appendicularians and copepods differed significantly, as a result of the influence of physical and biological factors. The negative impact of pelagic copepods on appendicularians was not found based on in situ data in the northwest continental shelf of SCS.

Copepods in Hypersaline Waters Worldwide:Diversity,Environmental,Social,and Economic Roles

1 Introduction Copepods are a group of small crustaceans,which play an important ecological role in aquatic ecosystems.They occupy different ecological niches in aquatic food webs,contributes to biogenic element cycles,and transfer of organic matter from primary producers to higher secondary consumers.Copepods also have the potential to

Studies on the chemical composition of some planktonic copepods in the Taiwan Strait

The chemical composition of marine zooplankton was studied though two seasonal cruises (August 1994and February 1995) in the Taiwan Strait. The carbon(C), nitrogen(N) and hydrogen(H) dry weight contents ofplanktonic copepods were in the range of 36. 24% -45. 63%,8 .50% -11. 37% and 4. 23%-6. 50% repectively.Data comparison among the three southern sea areas of China showed the same subtropical characteristics in the chemical composition of planktonic crustaceans. The seasonal changes of C and N contents and C/N ratio in the TaiwanStrait implied the different nutritional conditions in the open sea from those in the inner gulf.

Distribution of planktonic copepods in the Kuroshio area of the East Chine Sea to the southwest of Kyushu in Japan

The materials were obtained from the survey conducted in the Kuroshio area of the East China Sea to the Southwest of Kyushu in Japan (29°30'-32°00', 128°00'-130°'00'E) on board the R. V. Yoko Maru of Seikai Regional Fisheries Lab, Fisheries Agency, Japan in June 15~28, 1988 during China-Japan Joint Research on the Kuroshio. Zoo-plankton was collected by means of the North Pacific Net with model TSK flowmeter through vertical haul from 50 -Om. Temperature and salinity were measured with CTD. 134 species (including 4 spp. ) of planktonic copepods were preliminarily identified in the survey area. Most of them belonged to the tropical and subtropical species and a few of them were the warm-temperate species and eurytopic species. The main dominant species vteieOncaea venusta, Oithona plumifera, Clausocalanus furcatus, C. Arcuicornis, Paracaianus dculeatus, Oithona similis, Temara turbinata, Oncaea media, Undinula danvinii, Acartia negligent, Corycaeus speciosus, Scolecithrix danae, etc. The total number of individuals of planktonic copepods were about 367. 6 ind. /m3 on an average. The horizontal distribution of planktonic cope-pods was less in number but more in species in the main current area of the Kuroshio. The variations of growth and decline of the warm Kuroshio and the coastal current along China coast influenced the community structure and the distribution of planktonic copepods. Water temperature was one of principal controlling factors affecting the species composition and the quantitative distribution of planktonic copepods.

Effects of UV radiation on the RNA/DNA ratio of Copepods from Antarctica and Chile

The effect of ultraviolet （UV） radiation on marine organisms has been an important focus of recent research, with depletion of the ozone layer resulting in increased UV radiation at high latitudes. Several studies have identified negative impacts of UV radiation on the biology of zooplanktonic organisms. This study used the RNA/DNA ratio as a measure of stress in copepod assemblages from Fildes Bay in Antarctica and Quintay Bay on the central coast of Chile, two areas with high UV radiation but different photobiologic histories. Controlled time-light experiments were performed with copepods from the two locations, exposing them to white light, UV light, or darkness. The results showed different responses to UV radiation. Copepods from Fildes Bay showed a slow metabolic response to UV radiation after 4 and 8 h of exposure. Copepods from Quintay Bay showed a fast metabolic response after 4 h of exposure （4 orders of magnitude higher than that for Fildes Bay copepods） followed by a rapid return toward baseline after 8 h of exposure. These different responses probably reflect the time the eopepod assemblages have been exposed to increased UV radiation and the extent of adaptive stress responses to cope with that increased UV radiation. The results of this study show that the RNA/DNA ratio is a useful indicator of the physiologic status of marine organisms and is a useful tool to measure the effects of changing environmental conditions on marine ecosystems, such as those associated with global climate change.

Diversity and Abundance of Copepods in Taninthayi Coastal Waters, Myanmar

Diversity and abundance of copepods occurring in Taninthayi coastal waters were studied and analyzed from the samples collected by R/V DR.FRIDTJOF NANSEN during the Myanmar ecosystem survey 2018.Seventy-nine copepods species belonging to calanoids(51 species),cyclopoids(21 species),and harpacticoids(7 species)were identified in the copepods community of Taninthayi coastal waters.Copepods species number and density were high at the nearshore stations(Sts 799,842,788)and low at the offshore stations(Sts 846,802,823).The resulted diversity index values of copepods were varied from 2.61 to 3.78 in species diversity index(H'),from 0.89 to 0.97 in the evenness index(E'),and from 2.51 to 7.50 in species richness index(D').According to the correlation matrix,the abundance of copepods was positively correlated with temperature,chlorophyll a and fluorescence,and negatively correlated with salinity and oxygen.

Parasitic Copepods on Common Carp(Cyprinus carpio,L.1758)from Gradche Reservoir(Macedonia)

During the parasitological examinations of the common carp(Cyprinus carpio,L.1758)from the Gradche Reservoir(Macedonia),a total of 126 fish samples were examined,from which parasite infestation was determined in 87 fish(69.05%).In this research,the following parasitic copepods were identified:Ergasilus sieboldi,Ergasilus briani,and Lernaea cyprinacea.Ergasilus sieboldi was found on gills of common carp,with a prevalence of 1.461%,while the mean intensity was 2.357.Ergasilus briani was found on fins of common carp,with a prevalence of 1.879%,while the mean intensity was 38.274.Lernaea cyprinacea was found on the fins of common carp,with a prevalence of 0.552%,while mean intensity was 2,000.Our findings of Ergasilus sieboldi,Ergasilus briani,and Lernaea cyprinacea in common carp are considered as first records for Macedonia.At the same time,common carp is a new host for Ergasilus briani in Macedonian waters.

Impacts of CO_2-driven seawater acidification on survival,egg production rate and hatching success of four marine copepods

Ecological experiments were conducted to examine the effects of seawater containing elevated par- tial pressure of carbon dioxide （p CO2 800 × 10 -6 , 2 000 × 10 -6 , 5 000 × 10 -6 and 10 000 × 10 -6 ） on the survival and reproduction of female Acartia pacifica, Acartia spinicauda, Calanus sinicus and Centropages tenuiremis, which are the dominant copepods in the southern coastal waters of China. The results show that the effects of elevated p CO2 on the survival rates of copepods were species-specific. C. sinicus, which was a macro-copepod, had a higher survival rate （62.01%–71.96%） than the other three species （5.00%–26.67%） during the eight day exposure. The egg production rates of C. sinicus, A. spinicauda and C. tenuiremis were significantly inhibited by the increased p CO2 and the exposure time duration. There were significantly negative impacts on the egg hatching success of A. spinicauda and C. tenuiremis in the p CO2 2 000 × 10 -6 and 10 000 × 10 -6 groups, and, in addition, the exposure time had noticeably impacts on these rates too. This study indicates that the reproductive performances of copepods were sensitive to elevated p CO2 , and that the response of different copepod species to acidified seawater was different. Furthermore, the synergistic effects of seawater acidification and climate change or other pollutant stresses on organisms should be given more attention.

Preliminary study of the retention mechanism of planktonic copepods in the Jiulong Estuary in China

The horizontal and vertical distribution patterns of five planktonic copepods, Calanus sinicus, Acartia pacifica, Tortanus derjugini, Acartiella sinensis and Pseudodiaptomus poplesia, predominant in the Jiulong Estuary, were investigated from May 2003 to April 2004. The results showed that the distribution of these copepods was related to the tidal period but that each species had its own specific pattern. C. sinicus showed no tidal vertical migration behavior and was thought to be a non-resident species in this estuary. Among Acartia pacifica, T. derjugini,Acartiella sinensis, more individuals occurred in the surface than in the bottom waters during flood tide, and the pattern was reversed during ebb tide. The epibenthic copepod P. poplesia usually remained in the bottom waters in the upstream part of the estuary, but it displayed strong tidally-oriented vertical migration in the middle reaches of the estuary. Taking into account the hydrographic characteristics of the Jiulong Estuary, it was hypothesized that the planktonic copepods in this estuary had more or less adopted the mechanism of vertically migrating to the surface waters during flood tide in order to make use of the inflowing tide, and then sinking to the bottom during ebb tide to avoid being carried out of the estuary by net outflow.

Spatial and Temporal Variations of Pelagic Copepods in the North Yellow Sea

This study aims to analyze the spatial and temporal variations of the abundance and biodiversity of pelagic copepods and their relationships with the environmental factors in the North Yellow Sea(NYS). These variations were analyzed on the basis of the survey data of the NYS in four seasons from 2006 to 2007. A total of 31 copepod species that belong to 17 genera, 13 families and 4 orders were identified in the four seasons. Of these copepods, the species belonging to Calanoida is the most abundant component. The dominant species include Calanus sinicus, Centropages abdominalis, Paracalanus parvus, Acartia bifilosa, Oithona plumifera, and Corycaeus affinis. C. sinicus is the most important and widely distributed dominant species in all of the seasons. The dominant species have not shown any significant variation for the past 50 years. However, the richness of warm-water species increased. The abundance of copepods significantly varied among different seasons: the average abundance was higher in spring(608.2 ind m^(-3)) and summer(385.1 ind m^(-3)) than in winter(186.5 ind m^(-3)) and autumn(128.0 ind m^(-3)). Factor analyses showed a high correlation between the spatial distributions of dominant copepods and environmental parameters, and Chl-a was the most important factor that influenced the distribution of copepods. This research can provide the fundamental information related to zooplankton, especially pelagic copepods. This research is also beneficial for the long-term monitoring of zooplankton ecology in the NYS.

Dietary separation between co-occurring copepods in a food-limited tropical coral reef of the Sanya Bay

Food differentiation among coexistent species in the field is important strategy for copepods to acquire materials and maintain population stabilization.In situ diet analysis of co-occurring six copepod species in coral waters of the Sanya Bay was conducted using a PCR protocol based on 18 S ribosomal gene.Various prey organisms were uncovered,including dinoflagellate,diatom,green algae and plant,protozoa and metazoan.All these spatially coexisting six species showed different dietary diversity,with the food niche breadth(B)ranging from 1.00(Temora turbinate in morning)to 10.68(Calanopia elliptica in night).While food overlap between all these copepods were low,with the average value of the diet niche overlap index being approximately 0.09.Even temporally co-existing species sampled from the same time point fed on different groups of prey items with the food overlap index of 0.04 to 0.07 in midday and night but 0 in morning.As the most important dominant copepod in the Sanya Bay,Subeucalanus subcrassus seems to be capable to regulate its feeding,by exhibiting a rhythm of herbivorous feeding in midday and carnivorous feeding in morning and night,to better coordinate with other competitors for utilization of food resources.For most copepods,none of the prey items belonged to the dominant phytoplankton in the ambient water,indicating that copepod can better their survival by widening the choice of potential food resources in food limited environment.The dietary separation observed here might be important strategy for copepod to maintain population stabilization and thriving in the Sanya coastal waters.

Effect of Turbidity on Semi-Automatic Analysis of Copepod Size and Abundance Distribution in the Water Column

Automated image systems to characterize aquatic organisms improve research and enable fast response to environmental risk situations. In November 2015, a dam in Mariana City-MG (Brazil) collapsed and led to the disposal of mud tailings from the mining process to the Doce River. The accident resulted in several casualties and incalculable damage to surrounding communities and the environment. The mud increased water turbidity, an essential condition to the functioning of the image analysis systems, and directly affected the characterization of the organisms, making it impossible to distinguish copepods in the mud, due to the blurred outline. To get a quick response evaluating environmental situations, this work aimed to develop and test different algorithms characterizing and classifying copepods by their size (length and area) using in situ images acquired by the Lightframe On-Sight Keyspecies Investigation device. Field tests were carried out under different turbidity levels throughout the gradient observed in the coastal zone adjacent to the Doce River. The best algorithm reduced nearly 50% of the noise in some images when compared with manual treatment and led to 96% accuracy in measurement and counting. Semi-automated devices that perform post-processing corrections are suitable for fast environmental evaluation under high turbidity scenarios.

Grazing by microzooplankton and copepods on the microbial food web in spring in the southern Yellow Sea,China

Assessment of microzooplankton and copepods grazing pressure on picoplankton is a key requirement for resolving the microbial food web efficiency.Although microzooplankton grazing on picoplankton has been extensively studied,the impact of microzooplankton on different groups of picoplankton,i.e.,heterotrophic bacteria,Synechococcus and picoeukaryotes have rarely been compared.Furthermore,in the very few existing studies there is no consistent evidence of an enhancing or restraining effect of copepods on picoplankton.More studies are needed to improve our understanding of the influence of microzooplankton and copepod on picoplankton.Dilution incubations and copepod addition incubations were performed during a cruise to the southern Yellow Sea on May 16-29,2007.The bulk grazing of microzooplankton and the calanoid copepod Cal anus sinicus on phytoplankton,flagellates and picoplankton was estimated.Stations were divided into either eutrophic or oligotrophic according to the nutrient and biological parameters.Picoplankton comprised a large part of the diet of microzooplankton in the central oligotrophic area,while phytoplankton was the main food of microzooplankton in the coastal eutrophic area.In the central oligotrophic area,microzooplankton preferred grazing on Synechococcus.After copepod addition,ciliate abundance decreased while Synechococcus abundance increased(382%,64%and 64%at three experimental stations,respectively),indicating strong grazing pressure of microzooplankton on Synechococcus.Our results suggest that Synechococcus might be an essential carbon source the planktonic food web in the oligotrophic waters of southern Yellow Sea.

Seasonal variation and longitudinal distribution of copepods in the main river area of the Three Gorges Reservoir

The ecosystem of the Three Gorges in the Yangtze River was changed into an artificial lake(reservoir)ecosystem after impoundment in June 2003.We surveyed the seasonal variation and spatial distribution of copepods from April 2004 to January 2005 in order to provide data for clarifying the successional pattern of the ecosystem.From Jiangjin to Maoping,eight copepod species were collected and classified into Calanoida(2),Harpacticoida(1),and Cyclopoida(5).Among them,Mesocyclops pehpeiensis,M.leuckarti and Sinocalanus dorrii had a relatively wide distribution.No distinct difference in species number was found among the sampling sites,but the species composition was different.Species composition,distribution and density of copepods showed significant seasonal variations.In addition,copepod density showed an obvious gradient with the distance from the reservoir dam:the nearer to the dam,the denser the copepods.

The response of zooplankton abundance in saline meromictic Lake Shira to a change in circulation regime

The long-term data(1996-2021)on the summer abundances of the dominant zooplankton species(copepod Arctodiaptomus salinus(Daday,1885),rotifers Brachionus plicatilis(Müller,1786)and Hexarthra sp.)in saline Lake Shira were used to analyze the response of zooplankton to air temperature and a change in the circulation regime of the lake:breakdown and reestablishment of meromixis.All groups of zooplankton responded to prolonged summer elevated temperatures by increasing their abundance.During the breakdown of the stable stratification of Lake Shira(2015-2016),zooplankton abundance increased on average by a factor of two and amounted to 9×10^(5)inds./m^(2)in the water column for copepods.That increase coincided with similar responses of other components of the lake’s mixolimnion ecosystem,whose biomasses increased approximately two-fold during that period.After the reestablishment of the meromixis,the abundance of zooplankton decreased to previous values.Thus,the abundance of zooplankton is largely determined by weather(the effect of temperature)and ecological factors(mixing regime).

Molecular quantification of copepod Acartia erythraea feeding on different algae preys

Quantitative evaluation of the copepod feeding process is critical for understanding the functioning of marine food webs, as this provides a major link between primary producers and higher trophic levels. In this study, a molecular protocol based on quantitative polymerase chain reaction(qPCR) targeting 18S rDNA was developed and used to investigate the feeding and digestion rates of the copepod Acartia erythraea in a laboratory experiment using microalgae Thalassiosira weissflogii, Prorocentrum shikokuense, and Alexandrium catenella as prey. Although offered an equal encounter rate based on biovolume, prey uptake varied substantially among the three algal species, with the ingestion rate(IR) and digestion rate(DR) of A. erythraea differing significantly(P <0.001) based on both cell counting and qPCR detection. Acartia erythraea showed the highest IR(2.79×10~4 cells/(ind.·h)) and DR(2.43×10~4 cells/(ind.·h)) on T. weissflogii, and the lowest amounts of ingested P. shikokuense were detected. The highest assimilation rate(~90.64%, IR/DR) was observed in copepods fed with P. shikokuense. The qPCR method used here can help determine the digestion rate and assimilation rate of copepods by detecting cells remaining in the gut hence providing the possibility to examine trophic links involving key species in the marine ecosystem. Our results indicate that A. erythraea has diet-specific feeding performance in different processes, and a quantitative assessment of copepod feeding is needed to accurately determine its functional role in the energy and matter uptake from marine food webs.

桡足类消化酶活力的影响因子

桡足类消化酶活力的影响因子汤鸿，李少菁（厦门大学海洋系，３６１００５）ＦａｃｔｏｒｓＩｎｆｌｕｅｕｃｉｎｇｔｈｅＤｉｇｅｓｔｉｖｅＥｎｚｙｍｅＡｃｔｉｖｉｔｙｏｆＣｏｐｅｐｏｄｓ．￥ＴａｎｇＨｏｎｇ；ＬｉＳｈａｏｃｈｉｎｇ（Ｏ－ｃｅａｎｏｌｏｇｙＤｅ...

Abundance and biomass of meiobenthos in the spawning ground of anchovy (Engraulis japanicus) in the southern Huanghai Sea

A grid of 22 stations, giving a broad coverage of the spawning ground of anchovy in the southern Huanghai Sea was selected. Undis- turbed sediments were taken from sampling stations during the cruise in June 2003. The average abundance of meiofauna is (1 584± 686) ind./10cm2, with corresponding biomass (dwt) of (1 086±425)!μg/10cm2. The pattern of abundance of meiofauna is similar to the pattern of biomass. There are 65.88% meiofauna in 0￣2 cm sediments, 27.66% in 2￣5 cm sediments and 6.47% in 5￣8 cm sediments. The Spearman correlation analysis between meiofauna and environmental factors shows that abundance of meiofauna, free living ma- rine nematodes, benthic copepods has significant positive correlations with Chl-a. And the abundance of copepods has significant posi- tive correlations with several factors such as Chl-a, Pha-a, Chl-a plus Pha-a and organic matter. A total of 18 meiofauna groups are i- dentified. Nematode is the most dominant group, average abundance (1 404±670) ind/10cm2, accounting for 88.65%, and the follow- ing groups are also important: benthic copepods (5.48%), kinorhyncha (1.26%), polychaeta (1.07%). By biomass, dominant groups are nematodes (51.72%), polychaeta (21.84%), copepods (14.87%), ostracoda (4.92%), kinorhyncha (3.67%). A total of 90 species of ne- matodes are identified. The species composition of nematodes is listed based on selected two stations 7794 (coastal area) and 10694 (cold water mass in deep waters).

Biomass of meiobenthic in the Bohai Sea, China

A grid of 22 stations, giving a broad geographic coverage of the Bohai Sea and the Bohai Strait was selected. Undisturbed sediments were collected from sampling stations during cruises in June 1997, in September/October 1998 and again in April/May 1999. Based on the results of Juario (1975), the average biomass, 0.404 g/(m2a) of meiofauna (including nematode, harpacticoida, bivalve larvae, polycheata and kinorhyncha) in the Bohai Sea is given and accounts for 4.5 percent of the macrofauna in the Bohai Sea. The horizontal distribution of the biomass of meiofauna showed that it was higher at the stations of middle east part of the Bohai Sea and the strait in 1998 and 1999 cruises and it decreased at the stations near to the strait mouth and increased at Station B1 in 1999 cruise. The annual average production in the Bohai Sea is 3.636 g/m2 calculated in term of the formula P = 9B. Compared with the biomass of other sea areas in the world, the biomass of the Bohai Sea is similar but slightly lower. The individual average dry weight of nematodes given by different authors is analyzed.